The use of ultrasonic sound waves and electromagnetic fields to repel pests is well-known. See U.S. Pat. Nos. 4,616,351; 4,178,578; 4,802,057; 4,414,653; 4,870,779; D409,109; 5,930,946; and 6,400,995 and the patents cited in the foregoing patents, the contents of all of which are incorporated herein by reference. It is known that ultrasonic sound waves at a frequency normally inaudible to humans can be effective to repel pests such as rodents, rats, mice, squirrels, bats, insects, roaches, flies, fleas, crickets, spiders, ants, bees, mosquitos, centipedes, waterbugs, and other pests. Ultrasonic sound waves irritate and repel pests, it is believed by disrupting their nervous system, affecting their feeding and communication habits, and through irritation forcing them to leave the area. It is also useful to vary and change the ultrasonic sound waves in frequency and amplitude (or loudness) so the pests are less able to habituate to it, for example, instead of using a fixed high frequency, a constant or fixed sound can be put out for 2 or more minutes, then changed to a sweeping or varying or fluctuating sound, such as higher and lower frequencies from 25 to 75 kHz, to alter the frequency and amplitude (or loudness) and prevent the pests from becoming desensitized to the irritation. When the ultrasound is increased and decreased in amplitude or loudness and frequency in random or inconsistent patterns, it is harder for the pest to adjust to the annoyance. Also, different sound waves may target different pests, for example, higher ultrasonic waves can affect smaller pests, such as insects, while lower ultrasonic waves can affect larger pests such as mammals, such as rats, mice, bats and squirrels.
It is known in the prior art to plug an ultrasonic pest repeller unit into a wall outlet or wall socket. However, these units point straight out into the room and send out or radiate ultrasonic waves in a single direction or pattern. Ultrasonic waves generally radiate out in straight lines like audible sound waves and bounce or echo off non-absorbing materials, such as hard surfaces like solid wood, cupboard doors, large appliances, ceilings, walls, stone, metal, etc. However, softer materials such as carpeting, fabric, textiles, drapes, pillows, plastic foam, flexible foam, etc. tend to absorb sound waves. Most rooms are filled with furniture and other items that tend to absorb or block or deflect or reflect incident ultrasonic sound waves, leaving “shadow” areas on the far side of the furniture or other obstruction where the ultrasonic waves don't get to, leaving pests in those areas unirritated and unrepelled. The present invention is directed at reducing this problem.